zstack object implemented with zlib

coro/zstack_zlib.pyx

+# -*- Mode: Cython -*-
+
+class ZlibError (Exception):
+    "A problem with zlib"
+
+cimport zlib
+
+cdef class zstack:
+    cdef zlib.z_stream squish, unsquish
+    # this buffer is only used for compression
+    cdef unsigned char * buffer
+    cdef int buffer_size
+    def __init__ (self, int size=4*1024*1024):
+        cdef int r
+        self.squish.zalloc = NULL
+        self.squish.zfree  = NULL
+        self.squish.opaque = NULL
+        self.unsquish.zalloc = NULL
+        self.unsquish.zfree  = NULL
+        self.unsquish.opaque = NULL
+        self.buffer = <unsigned char *>PyMem_Malloc (size)
+        if not self.buffer:
+            raise MemoryError
+        self.buffer_size = size
+        r = zlib.deflateInit (&self.squish, zlib.Z_BEST_SPEED)
+        if r != zlib.Z_OK:
+            raise ZlibError (r)
+        r = zlib.inflateInit (&self.unsquish)
+        if r != zlib.Z_OK:
+            raise ZlibError (r)
+
+    def __dealloc__ (self):
+        zlib.deflateEnd (&self.squish)
+        zlib.inflateEnd (&self.unsquish)
+        PyMem_Free (self.buffer)
+
+    cdef size_t deflate (self, void * base, size_t size):
+        zlib.deflateReset (&self.squish)
+        self.squish.next_in = <unsigned char *> base
+        self.squish.avail_in = size
+        self.squish.next_out = self.buffer
+        self.squish.avail_out = self.buffer_size
+        zlib.deflate (&self.squish, 1)
+        # return the compressed size
+        return self.buffer_size - self.squish.avail_out
+
+    cdef size_t inflate (self, void * dst, size_t dsize, void * src, size_t ssize):
+        zlib.inflateReset (&self.unsquish)
+        self.unsquish.next_in = <unsigned char *>src
+        self.unsquish.avail_in = ssize
+        self.unsquish.next_out = <unsigned char *>dst
+        self.unsquish.avail_out = dsize
+        zlib.inflate (&self.unsquish, 1)
+        # return the uncompressed size
+        return dsize - self.unsquish.avail_out